Shaft extension for electric motors



Jan. 3, 950 v W, HEATH-Q 2,493,349

SHAFT EXTENSION FOR ELECTRIC MOTORS Filed April 24, 1944 CP1 William C. Heath INVENTOR.

ATTORNEY.

Patented Jan. 3, 1.950 'Y UNITED STATES PATENT OFFICE SHAFT EXTENSION FOR ELECTRIC MOTORS William C. Heath, Shorewood, Wis., assignor to A. 0. Smith Corporation, Milwaukee, Wis., a corporation of New York Application April 24, 1944, Serial No. 532,459

4 Claims. (Cl. S18-325) 1 2 This invention relates to a shaft extension for Fig. 6 is a fragmentary section taken on the line an electric motor drive shaft and has particular 6-6 of Fig. 1. use in connection with the switch operating Referring to the drawing, the electric motor mechanism described and -claimed in the cohas ahousing I carrying a longitudinally disposed pending application of Lloyd Yost entitled l motor shaft 2 with a shaft extension 3. The Switch operating mechanism, filed March 27, shaft 2 and extension 3 rotate in suitable bear- 1943, Serial No. 480,785, now Patent No. 2,394,283. ings 4 provided at each end of the housing I.

Heretofore the switch operating mechanism of A stator 5 is suitably secured to the inside of the the application referred to has been employed housing I and a rotor 6, preferably of the squirrel with a motor shaft that is made longer than the 10 cage type, is secured to the shaft 2 to complete usual shaft and bored out and otherwise mathe motor parts for the purposes of this applichined to accommodate the mechanism. This incation.

volves a great deal of machining resulting in in- A cover I provides a closure for one end of creased costs in producing the motor. housing I and may be secured thereto by screws In order to decrease the cost of production and l5 or other means. An inturned flange 8 disposed eliminate excessive, scrap material the invention at the central portion of cover 1 provides a seat proposes to provide a short motor shaft and then for bearing 4 in which the outer end of shaft weld thereto a pre-formed shaft extension extension 3 is journaled.

adapted to accommodate the switch mechanism. Suitable air openings 9 may be provided in cover The invention may be carried out by pressing 20 'l thlOugh Which ail' may be drawn by fan l0 t0 two sheet metal members to the proper comple.. e001 the motor parts. The air is forced through mentary semi-tubular shape and then welding Spaces between the stator and rotor and stator them together along longitudinal lines to provide `and housing and flows out through openings Il the shaft extension that is to be welded to the at the Other end 0f the motor.

end of the motor shaft. The shaft extension 3 of shaft 2 terminates inl One object of the present invention is to proa Switch hOUSng l2 having its irme? plate '3. vide a substantially light Weight shaft, extension preferably of insulating material, secured to cover that can withstand hard use in service- 1 of the motor by screws I4. The housing I2 is Another object is to provide a shaft extension o covered by a Suitable ap 'fi that can be fabricated Without excessive and 3 AS shown and descrbed 1n the co'pendlng apcostly machining operations plication of Lloyd Yost for Switch operating A further object is to provide a shaft extension mechanism, heretofore refered to the Switch that can be readily assembled with a motor shaft. mechanism in general compmses the spring arm These and other objects of the invention will '6 Secured to plate I3 Carrying Contact n dis' appear in the description of an embodiment of the invention as employed with an electric motor shaft and illustrated in the accompanying drawing.

In the drawing: 4o

Figure 1 is a longitudinal central section of a motor embodying the invention and showing the extension welded to the motor shaft;

Fig. 2 is a perspective view of one of the shaft extension halves after forming and before 45 welding;

Fig. 3 is a transverse section taken on the line 3-3 of Fig. 2 of two halves positioned for Welding;

secured to plate I3.

Spring arm I6 is biased to normally open the into engagement as shown by a push rod 2n disposed axially of the central tubular portion 2| of extension 3 and axially reciprocated by the governor 22 and spring 23. The governor 22 in turn is actuated by the speed of the motor shaft 2. The engagement and disengagement of contacts I'I yand I8 by means of the governor operated mechanism closes and opens a circuit, not shown, for the purposes disclosed in the co-pending application above referred to.

Referri o eg. 4 1s a armar section after the welding 50 invensmfleZeerytsu and trimming operations' bod y pressed from sheet metal and fo Flg' 5 1S 'a lfmgltudmal s601710 taken on 1m@ semi-cylindrical half members 24. slulcfzlle'idgsf gg '5.-5 of Fig. 4 showing the finished shaft extenhalf member Shown in Fig. 2 The half mems1on anda portion of the motor shaft positioned bers are complementary to each other and are for Welding; and 5 joined at their marginal edges by welds 25 ex- 35 posed to engage contact I8 on the bracket I9 also contacts I1 and I8, and the latter are moved tending longitudinally of the two members as illustrated in Figs. 4 and 5.

In the embodiment illustrating the invention the central cylindrical portion 2| extends for substantially the entire length ofthe extension 3. A shoulder 26 of the extension 3 engages the bearing 4 in which the outer end of extension 3 rotates.

A transverse bar 27 extends through opposite slots 28 in the wall of the extension 3 and the slots extend longitudinally of the extension to allow reciprocation of the bar 21 axially of the extension. The inner end of push rod 2D is secured to the center of bar 2! to effect axial movement of rod 2li by the governor in one direction and by the spring 23 in the other direction.

In order to provide slots 28 ears 29 are struck radially inwardly of each half member 24 and outwardly toward the outer end of the extension 3 as illustrated in the drawings. The ears 29 have registering semi-circular slots in their adjacent edges and provide the inner bearing for rod 20. They also serve as the inner abutment for the spring 23' disposed around the rod 20.

A head 30 provided on the outer end of push rod 20 has a sliding bearing in the reduced outer end of member 3 and provides the outer abutment for spring 23.

Grooves 3| are disposed on the outer surface of each half member 24 to retain springs 32 of governor 22 when the motor is traveling at low speeds.

The inner end 33 of each member 24 of the shaft extension 3 is fabricated in a manner to provide for electric ash welding of the same to the end of motor shaft 2.

Before the shaft extension 3 is assembled with the motor shaft 2, the end of the motor shaft is machined out to provide a cylindrical end flange 34 for welding.

The shaft extension is then butt welded to the motor shaft 2, preferably by flash welding the end 33 of the shaft extension to the end flange 34 of the motor shaft. The weld is then machined ush with the surface of the shafts and the rotor lamination forced onto the shaft against the shoulder 35 at the inner end of the portion 2| of the extension.

The switch operating mechanism and fan IU are then assembled with the shaft extension. The fan I3 may be secured to the tubular portion 2| in any suitable way such as by spot welding. In some types of motors the fan may be dispensed with.

The motor shaft is then assembled in the housing I and the end cover 'l containing the bearing 4 is secured to the motor housing by several screws 36 one of which is shown.

The invention provides an emcient shaft that may be employed with a switch operating mechanism. The shaft is economically fabricated as considerable savings in labor and metal are made possible by substantially eliminating machining operations.

Various embodiments of the invention may be employed within the scope ofthe accompanying claims.

I claim:

1. In combination in an electric motor, a housing, a solid shaft section journaled in the drive end of said housing, a pressed sheet metal tubular extension secured to said shaft section and journaled in the other end of the housing, a stator in said housing, a rotor xed on the composite shaft against an abutment on the tubular extension, and switch actuating mechanism carried by said tubular extension for controlling said motor.

2. In an electric motor, a tubular pressed metal shaft extension for carrying switch actuating mechanism including a spring biased longitudinally reciprocating central push rod and a transverse governor bar for operating the same, said tubular extension having slots in its opposite sides for receiving said transverse bar and ears struck inwardly from said slots to provide a central support for said push rod and a xed support for one end of a biasing spring on said rod.

3. In combination with a motor, a housing, a shaft journaled in said housing, a pressed sheet metal tubular member secured to said shaft and having diametrically opposed slots in the walls thereof, a governor mounted on said member and having a transverse bar extending through the slots in said member, a longitudinally reciprocating push rod biased within said member and engaging said transverse bar, and switch mechanism actuated by the reciprocating push rod through the operation of the governor upon rotation of the shaft and member to control said motor.

4. In combination with a motor, a housing, a solid shaft journaled in one end of said housing, a pressed sheet metal tubular member secured to the inner end of said shaft and journaled in the other end of said housing and having diametrically opposed slots in the walls thereof, a governor assembled with said tubular member and comprising a spring disposed around the member and a transverse bar connected to said spring and projecting through said slots with the slots being of a length providing for reciprocation of the bar in a direction longitudinal of said member, a spring biased longitudinally reciprocating push rod supported axially within said member and secured at one end to said bar and projecting outwardly of said member at the other end, and a switch mechanism mounted on said housing and engaged by the outer end of the push rod through the operation of the governor upon rotation of the shaft and tubular member to control said motor.

WILLIAM C. HEATH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 516,651 Hochhausen Mar. 20, 1894 848,292 Dawson Mar. 26, 1907 2,067,282 Padgett Jan. 12, 1937 2,083,411 Swanson June 8, 1937 2,099,050 Chamberlain Nov. 16, 1937 FOREIGN PATENTS Number Country Date 344,340 Great Britain Mar. 2, 1931 

